From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: Alan Stern <stern@rowland.harvard.edu>
Subject: Re: [PATCH -mm 6/7] PM: Remove power_state.event checks from suspend core code
Date: Sun, 17 Jun 2007 21:26:30 +0200
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Cc: David Brownell <david-b@pacbell.net>,
       Andrew Morton <akpm@linux-foundation.org>, Greg KH <greg@kroah.com>,
       LKML <linux-kernel@vger.kernel.org>, Pavel Machek <pavel@ucw.cz>
References: <Pine.LNX.4.44L0.0706142157420.30954-100000@netrider.rowland.org> <200706152357.58613.rjw@sisk.pl>
In-Reply-To: <200706152357.58613.rjw@sisk.pl>
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On Friday, 15 June 2007 23:57, Rafael J. Wysocki wrote:
> On Friday, 15 June 2007 04:00, Alan Stern wrote:
> > On Fri, 15 Jun 2007, Rafael J. Wysocki wrote:
> > 
> > > On Thursday, 14 June 2007 16:21, David Brownell wrote:
> > > > On Wednesday 13 June 2007, Rafael J. Wysocki wrote:
> > > > > From: Rafael J. Wysocki <rjw@sisk.pl>
> > > > > 
> > > > > The suspend routines should be called for every device during a system sleep
> > > > > transition, regardless of the device's state, so that drivers can regard these
> > > > > method calls as notifications that the system is about to go to sleep, rather
> > > > > than as directives to put their devices into the 'off' state.
> > > > 
> > > > Did you audit all the drivers to make sure this won't break things?
> > > > Like for example through inappropriate pci_save_state() calls?
> > > 
> > > I did, but not very carefully.
> > > 
> > > > I'd really expect this patch would break things...
> > > 
> > > Well, in that case I'll have a closer look at them.
> > 
> > It might not be all that bad.  One would expect problems to occur only 
> > in cases where devices were already suspended at the time of a system 
> > sleep transition.  Since relatively few drivers currently implement 
> > runtime PM -- and those that do are likely to be more careful about 
> > not blindly making state changes -- there might not be too much 
> > trouble.
> 
> Yes, in fact I've had no problems related to that so far (tested the patch on
> four different machines).

It seems the drivers for which that could be relevant do the checks as needed.

Greetings,
Rafael


-- 
"Premature optimization is the root of all evil." - Donald Knuth
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